The microstructures exhibited by gas atomized powders of two alloys, Al-6Gd-6Ni-1Fe and Al-5Y-10Ni (at. %), have been analyzed using electron microscopy. It was found that the microstructure depends critically on the particle size obtained during atomization. Small particles (<1μm) tend to be completely amorphous. Larger particles (1–10μm) can also be amorphous, but often contain a mixture of amorphous material and crystalline Al. Three distinct morphologies are observed: nanocrystalline particles, fractal and dendritic growths embedded in an amorphous matrix. The yet larger particles (>30μm) are often fully crystalline, consisting of fine interspersed Al and intermetallic grains.